linux-kernel - Re: [PATCH v2] um: Allow building and running on older hosts

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Date:   Fri, 26 May 2017 00:34:31 +0200
From:   Richard Weinberger <richard@....at>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Thomas Meyer <thomas@...3r.de>
Cc:     linux-kernel@...r.kernel.org, elicooper@....com,
        Jeff Dike <jdike@...toit.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-devel@...ts.sourceforge.net>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-user@...ts.sourceforge.net>
Subject: Re: [PATCH v2] um: Allow building and running on older hosts

Thomas, Florian,

Am 26.05.2017 um 00:28 schrieb Florian Fainelli:
> On 05/25/2017 12:51 PM, Thomas Meyer wrote:
>>
>>> Am 25.05.2017 um 20:36 schrieb Florian Fainelli <f.fainelli@...il.com>:
>>>
>>> Commit a78ff1112263 ("um: add extended processor state save/restore
>>> support") and b6024b21fec8 ("um: extend fpstate to _xstate to support
>>> YMM registers") forced the use of the x86 FP _xstate and
>>> PTRACE_GETREGSET/SETREGSET. On older hosts, we would neither be able to
>>> build UML nor run it anymore with these two commits applied because we
>>> don't have definitions for struct _xstate nor these two ptrace requests.
>>
>> Btw. what soy you mean with older host? I need to revert two commits to make an UML kernel work again on a Fedora 25 installation.
> 
> This is centos 6.9, so kernel 2.6.32 and glibc 2.12, this neither has
> xstate nor PTRACE_GETREGSET/SETREGSET, hence this patch.

Commits a78ff1112263 and b6024b21fec8 are broken.
You see two different issues.
Eli, please have a look too.

Thanks,
//richard